Case Study

Reflecting on your last office session, you recall several pediatric visits. Among these was a visit from a six-month-old infant who was brought in for a checkup and completion of papers for the Women, Infants and Children (WIC) program. You ordered blood work for this infant, because it was required by the program. While most of these blood draws for infants in the WIC program are normal, on occasion, anemia is detected. You begin to wonder if it might be worthwhile to screen all pediatric patients for anemia rather than miss an occasional case.

Questions

1. Which of the following statements is/are correct regarding iron deficiency anemia?

   A. Mild iron deficiency (hemoglobin more than 10.5 g per dL [105 g per L]) in the absence of symptoms has only minor health consequences.

   B. Sampling of capillary blood specimens yields results comparable to those from venous blood specimens.

   C. Older children and adolescent groups with an increased prevalence of iron deficiency anemia include immigrants from developing countries.

   D. Correction of more severe iron deficiency anemia (hemoglobin less than 10.5 g per dL) in high-risk infants is associated with improved mental and physical development.

2. Which one of the following statements is correct regarding screening for iron deficiency anemia among pediatric patients?

   A. The USPSTF recommends screening for iron deficiency anemia for all infants from high-risk groups between the ages of six and 12 months.

   B. The USPSTF recommends screening for iron deficiency anemia for all infants less than 12 months of age.

   C. The USPSTF recommends screening for iron deficiency anemia for all children from high-risk groups between the ages of two and 10 years.

   D. The USPSTF recommends screening for iron deficiency anemia for all children at least once between the ages of two and 10 years.

   E. The USPSTF recommends screening for iron deficiency anemia for all children at least once before beginning elementary school.

3. Which one of the following additional laboratory parameters is most useful in the detection of iron deficiency anemia?

   A. Mean corpuscular volume.

   B. Red blood cell distribution width.

   C. Serum ferritin.

   D. Serum iron.

   E. Transferrin.

Answers

1. The answers are A, C and D: evidence of clinical benefit from correction of iron deficiency among older children is limited. Results from studies of clinical outcomes following iron supplementation among older children have also reported inconsistent findings for cognitive improvements.^1–3 Multiple observational studies have demonstrated an association between iron deficiency anemia and abnormal growth and development, but it is unclear how much of this is directly attributable to iron deficiency rather than to other environmental factors (e.g., poverty, poor nutrition).

Significantly better mental and motor development after four months of therapy among high-risk children with hemoglobin levels less than 10.5 g per dL^4,5 has been demonstrated in the largest of controlled trials on the benefits of correcting iron deficiency, although some other studies have produced inconsistent results.

Studies of malnourished children in developing countries show enhanced growth and weight gain following iron supplementation.^6,7 However, whether such results can be generalized to the populations in the United States is uncertain.

While capillary blood sampling is often preferred because of the ease of collection, venous specimens are more reliable for the detection of iron deficiency anemia. Results from one study revealed the capillary microhematocrit to have a sensitivity of 90 percent and a specificity of 44 percent when compared with values obtained from venous blood with an automated cell counter.⁸ Children and adolescents who have recently immigrated from developing countries should be screened for iron deficiency anemia.⁹

2. The answer is A : the USPSTF recommends that high-risk infants be screened for iron deficiency anemia between six to 12 months of age. Screening for iron deficiency anemia is not recommended in the general infant population because of low overall prevalence. The Centers for Disease Control and Prevention has developed specific criteria for anemia: hemoglobin levels less than 11.0 g per dL (110 g per L) for children between six months and five years of age.¹⁰ In 1993, it was estimated that the prevalence of iron deficiency anemia among children younger than five years was less than 3 percent and most cases were mild¹¹; however, among high-risk groups, the prevalence may be 10 to 30 percent.¹⁰ Increased prevalence of iron deficiency anemia occurs among blacks, American Indians, Alaska Natives, persons of low socioeconomic status, preterm and low-birth-weight infants, immigrants from developing countries, and infants whose primary nutritional source is unfortified cow's milk.

Strategies to prevent iron deficiency anemia among infants are recommended. Family physicians should discuss issues of infant nutrition with expectant and new parents and encourage the consumption of iron-fortified formulas and cereals, or encourage breast-feeding supplemented with iron-fortified cereals between the ages of four to six months.¹²

3. The answer is C: while each of the laboratory parameters listed is useful in arriving at a diagnosis of iron deficiency, only serum ferritin is sufficiently sensitive and specific to be useful in identifying anemic patients.^5,13 Mild iron deficiency states may not affect hemoglobin levels.¹⁴